The Theory of Plate Tectonics

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Vocabulary

Plates - the separate sections of the lithosphere
Scientific Theory - a well tested concept that explains a wide range of observations
Plate Tectonics - the geological theory that states that the Earth's plates are constantly in motion
Faults - breaks in the Earth's crust where rocks have slipped past each other
Transform Boundary - a place where two plates slip past each other, moving in opposite directions
Divergent Boundary - the place where two plates move apart
Rift Valley - a deep valley which forms along divergent boundaries
Convergent Boundary - the place where two plates come together

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A Theory of Plate Motion

• Plate tectonics

  • Driven by convection currents in the mantle
    • Convection currents rise in the asthenosphere and spread out in the lithosphere

Plate Boundaries

• Transform Boundaries

  • Earthquakes will occur along these boundaries

• Divergent Boundaries

  • Occur along the mid-ocean ridge
  • occurs on land
    • Rift valleys occur near divergent boundaries

• Convergent Boundaries

  • When 2 plates converge, they cause a collision
    • Brings oceanic crust and oceanic crust
    • Brings Continental crust and oceanic crust
    • Brings Continental crust and continental crust
  • Density determines which plate comes on top
  • creates mountain ranges

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